In electrical panelboards containing circuit breakers, it is sometimes desirable to secure the circuit breakers to the panelboard so that the circuit breakers cannot be removed or even loosened to cause an interruption in the electrical power being supplied to critical equipment, such as the equipment in a data center. It is particularly desirable to permit the circuit breakers to be secured to the panelboard without the need to order special circuit breakers for that purpose, i.e., to permit virtually any standard circuit breaker to be secured to the panelboard. When the circuit breakers have already been installed, it is desirable to be able to secure the breakers to the panelboard without removing the circuit breakers, without requiring any special tools, and using a procedure that is safe for the installing personnel.